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Re: Systemtap + tracing processes inside a qemu guest


On Mon, Oct 10, 2011 at 09:35:30AM -0400, Frank Ch. Eigler wrote:
> "Richard W.M. Jones" <rjones@redhat.com> writes:
> 
> > [...]
> > However to get the complete picture I'd like to
> > instrument the daemon too.  The aim would be to get timing information
> > across both the host program and the daemon:
> >
> >   0.001s program event #1 send message
> >   0.005s daemon event #1 receive message
> >   0.010s daemon event #2 send reply
> >   0.025s program event #2 receive reply
> > [...]
> > What's possible at the moment?
> 
> You're looking for probing two separate systems (the host and the
> guest) together.  The general model does not stretch that far right
> now (and probably would not be easy to extend it that way).  The
> closest thing would be running separate scripts, one on the host, and
> one on the guest via --remote, and merging the events together after
> the fact.

Can you point me to an example of using --remote in this simpler case
(just into a qemu guest)?

Could events from inside the qemu guest be somehow transferred to the
host kernel so that we can collect them all in one place?  (I don't
really know exactly how this works ...)

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org


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